From owner-freebsd-hackers@FreeBSD.ORG  Sun May  8 12:26:02 2005
Return-Path: <owner-freebsd-hackers@FreeBSD.ORG>
Delivered-To: freebsd-hackers@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP
	id 07B0416A4E1; Sun,  8 May 2005 12:26:02 +0000 (GMT)
Received: from freebee.digiware.nl (dsl439.iae.nl [212.61.63.187])
	by mx1.FreeBSD.org (Postfix) with ESMTP
	id C9E5243D6A; Sun,  8 May 2005 12:25:59 +0000 (GMT)
	(envelope-from wjw@digiware.nl)
Received: from [212.61.27.74] (beck.digiware.nl [212.61.27.74])
	by freebee.digiware.nl (8.13.1/8.13.1) with ESMTP id j48CPouD002322;
	Sun, 8 May 2005 14:25:51 +0200 (CEST)
	(envelope-from wjw@digiware.nl)
Message-ID: <427E05D2.2060706@digiware.nl>
Date: Sun, 08 May 2005 14:28:02 +0200
From: willem jan withagen <wjw@digiware.nl>
Organization: Digiware
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US;
	rv:1.7.2) Gecko/20040804 Netscape/7.2 (ax)
X-Accept-Language: nl, en-us, en
MIME-Version: 1.0
To: Steven Hartland <killing@multiplay.co.uk>
References: <069901c54bfd$2967ba40$7f06000a@int.mediasurface.com>
	<427D5AA0.1080609@withagen.nl>
	<002b01c553be$93a5b790$b3db87d4@multiplay.co.uk>
In-Reply-To: <002b01c553be$93a5b790$b3db87d4@multiplay.co.uk>
Content-Type: text/plain; charset=us-ascii; format=flowed
Content-Transfer-Encoding: 7bit
X-Mailman-Approved-At: Sun, 08 May 2005 12:28:35 +0000
cc: freebsd-hackers@freebsd.org
cc: freebsd-current@freebsd.org
cc: Willem Jan Withagen <wjw@withagen.nl>
Subject: Re: Very low disk performance Highpoint 1820a
X-BeenThere: freebsd-hackers@freebsd.org
X-Mailman-Version: 2.1.1
Precedence: list
List-Id: Technical Discussions relating to FreeBSD
	<freebsd-hackers.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
	<mailto:freebsd-hackers-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-hackers>
List-Post: <mailto:freebsd-hackers@freebsd.org>
List-Help: <mailto:freebsd-hackers-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
	<mailto:freebsd-hackers-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Sun, 08 May 2005 12:26:02 -0000

Steven Hartland wrote:
> If that where the case it would have been it wouldn't have been
> 46Mb/s it would have been 543Mb/s, just tested it for you :P
>>> I've just finished putting together a new server box spec:
>>> Dual AMD 244, 2GB ram, 5 * Seagate SATA 400GB on a
>>> Highpoint 1820a RAID 5 array.
>>
>>
>>> 5.4-STABLE Highpoint 1820a RAID 5 ( 5 disk )
>>> 655360000 bytes transferred in 13.348032 secs (49097875 bytes/sec)
>>
>> You're only transfering 640M in 2GB of RAM, big chance that you're 
>> testing memory/buffercode-speed in stead of testing diskspeed.

Still I would argue that if you do not use a write size larger than what 
you have as real memory, that buffering in real memory is going to play 
a role....

Other than that I find 50Mb/s is IMHO reasonable high value for a RAID5 
in writting. But it would require substantial more organised testing. DD 
is nothing more than a very crude indication of what to expect in real life.

--WjW